Consolidated Statements Of Comprehensive Income - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Statement of Comprehensive Income [Abstract]
Net income		$ 40,067	$ 20,952	$ 24,570
Net change in unrealized gains (losses) on available-for-sale securities:
Net change in unrealized gains (losses) on available-for-sale securities, net of tax of $1,212, $1,873, and ($4,275), respectively		(2,251)	(3,479)	7,938
Net reclassification adjustment for gains included in net income, net of tax of $18, $1, and $158, respectively	[1]	(33)	(3)	(293)
Net change in unrealized gains (losses) on available-for-sale securities, net of tax		(2,284)	(3,482)	7,645
Net change in unrealized gains (losses) on cash flow hedging derivatives:
Net change in unrealized gains (losses) on cash flow hedging derivatives, net of tax of $343, $825, and $2,431, respectively		(637)	(1,533)	(4,515)
Net reclassification adjustment for effective portion of cash flow hedges included in interest expense, net of tax of ($709), ($593), and ($600), respectively	[2]	1,317	1,102	1,114
Net change in unrealized gains (losses) on cash flow hedging derivatives, net of tax		680	(431)	(3,401)
Postretirement plans:
Net actuarial loss, net of tax of $127, $21, and $225, respectively		(235)	(39)	(418)
Reclassification of amortization of net unrecognized actuarial loss and of prior service cost included in net periodic cost, net of tax of ($83), ($84), and ($51), respectively	[3]	152	155	96
Net gain (loss) on postretirement plans, net of tax		(83)	116	(322)
Other comprehensive income (loss)		(1,687)	(3,797)	3,922
Comprehensive income		$ 38,380	$ 17,155	$ 28,492

[1] (1) Reclassified into the consolidated statements of income within net gain on sale of securities.

[2] (2)Reclassified into the consolidated statements of income within interest on subordinated debentures.

[3] (3) Reclassified into the consolidated statements of income within salaries and employee benefits.